1. Field of the Invention
This invention relates to pipeline pigs of the type formed about a central shaft of flexible plastic material plastic and is particularly directed to an improved means of supporting a flange on the rearward end of the shaft.
For information relating to the use of pipeline pigs, reference may be had to the application 90,628, now Patent 4,275,475.
2. Description of the Prior Art
The use of pipeline pigs, and their construction, has long been known in the petroleum industry. Generally speaking, a pipeline pig is an apparatus which is inserted into a pipeline and travels through the line, usually by the movement of liquids or gases in the line, to accomplish purposes such as cleaning the interior of the line, removing paraffin, separating one type of fluid from another, removing entrapped water, inspecting the pipeline and so forth. The present invention is directed toward a type of pipeline pig which is formed primarily of plastic. Various cup-shaped devices may be employed on a pipeline pig for accomplishing the various services desired; and in the arrangement of the present invention, the working elements are assembled on an elongated cylindrical shaft. After the elements are assembled on the shaft, means must be provided for retaining them on the shaft and this is the objective of the present invention. While others have provided various devices for assembling the working elements of a pipeline pig onto a shaft, the present invention is unique in the provision of means employing a minimum of parts and yet retaining maximum strength of the assembled pipeline pig.